libieee1284 exclusive access

theNbomr · 04-13-2007, 07:33 PM

I hope this isn't too esoteric but I'm pretty well at wits end on this.

I am trying to use the ieee1284 library to build a tool for accessing parallel ports in some non-standard ways. The docs are fairly clear and my code builds cleanly, but I cannot get around the problem of exclusive access denial.
I set the environment variable LIBIEEE1284_DEBUG="1", and run th following code as root:

Code:

#include    <stdio.h>
#include    <stdlib.h>
#include    <sys/types.h>
#include    <sys/stat.h>
#include    <fcntl.h>

#include    <ieee1284.h>

int     main( int argc, char * argv[] ){

int     lp;

unsigned char byte;
unsigned int  baseAddr;
int         i;

struct parport_list lpList;
struct parport    * port;

int           capabilities;
int           portStatus;


    if( argc < 2 ){
        printf( "No output byte\n" );
        exit(1);
    }

    sscanf( argv[1], "%i", &byte );
    printf( "Outp byte: %02X\n", byte );
    
    ieee1284_find_ports( &lpList, 0 );
    for( i = 0; i < lpList.portc; i++ ){
        port = lpList.portv[i];
        printf( "      Name[%d] = %s\n",   i, port -> name );
        printf( "  BaseAddr[%d] = %04X\n", i, port -> base_addr );
        printf( "hiBaseAddr[%d] = %04X\n", i, port -> hibase_addr );
        printf( "  Filename[%d] = %s\n\n", i, port -> filename );
    
    }      
    
    if( lpList.portc ){
        port = lpList.portv[0];
        baseAddr = port -> base_addr;
    }
    else{
        printf( "No ieee1284 port\n" );
        exit(1);
    }
    
    /*
    **  Exclusive access fails at ieee1284_claim....
    **
    ** portStatus = ieee1284_open( port, 0, &capabilities );
    */
    portStatus = ieee1284_open( port, F1284_EXCL, &capabilities );
    
    printf( "Open Status: %d\n", portStatus );
    printf( "Open Capabilities: %04X\n", capabilities );
    if( capabilities & CAP1284_RAW ){
        printf( "CAP1284_RAW, " );
    }
    if( capabilities & CAP1284_NIBBLE ){
        printf( "CAP1284_NIBBLE, " );
    }
    if( capabilities & CAP1284_BYTE ){
        printf( "CAP1284_BYTE, " );
    }
    if( capabilities & CAP1284_COMPAT ){
        printf( "CAP1284_COMPAT, " );
    }
    if( capabilities & CAP1284_ECP ){
        printf( "CAP1284_ECP, " );
    }
    if( capabilities & CAP1284_ECPRLE ){
        printf( "CAP1284_ECPRLE, " );
    }
    if( capabilities & CAP1284_ECPSWE ){
        printf( "CAP1284_ECPSWE, " );
    }
    if( capabilities & CAP1284_BECP ){
        printf( "CAP1284_BECP, " );
    }
    if( capabilities & CAP1284_EPP ){
        printf( "CAP1284_EPP, " );
    }
    if( capabilities & CAP1284_EPPSWE ){
        printf( "CAP1284_EPPSWE, " );
    }
    if( capabilities & CAP1284_IRQ ){
        printf( "CAP1284_IRQ, " );
    }
    if( capabilities & CAP1284_DMA ){
        printf( "CAP1284_DMA, " );
    }
    printf( "\n" );

    /* Something on the net said try this, but it makes no diff...
    */
    ieee1284_free_ports( &lpList );


    portStatus = ieee1284_claim( port );
    printf( "Claim Status: %d\n", portStatus );
    if( portStatus & E1284_SYS ){
        perror( "ieee1284 Claim: " );
        exit(1);
    }
    

    ieee1284_write_data( port, byte );
    printf( "WriteData Status: %d\n", portStatus );
    if( portStatus & E1284_SYS ){
        perror( "ieee1284 WriteData: " );
        exit(1);
    }


    ieee1284_release( port );
    printf( "Release Status: %d\n", portStatus );
    if( portStatus & E1284_SYS ){
        perror( "ieee1284 Release: " );
        exit(1);
    }


    
    portStatus = ieee1284_close( port );
    printf( "\nClose Status: %d\n", portStatus );

    
    exit(0);
}

As far as I can tell, I start out with no loadable modules that would want to access the parallel port, so I don't see where there should be any contention for the hardware or device file (/dev/parport0)

The output from the code, including the driver debug output:

Code:

./lptTest2 0x0ff
Outp byte: FF
/dev/parport0 is accessible
We can use ioperm()
/dev/port is accessible
/dev/lp0 is accessible
This system has /proc/sys/dev/parport
      Name[0] = parport0
  BaseAddr[0] = 0378
hiBaseAddr[0] = 0778
  Filename[0] = /dev/parport0

==> ieee1284_open
==> init_port
Got 0 from ppdev init
<== 0
Open Status: 0
Open Capabilities: 01EE
CAP1284_NIBBLE, CAP1284_BYTE, CAP1284_COMPAT, CAP1284_ECP, CAP1284_ECPRLE, CAP1284_ECPSWE, CAP1284_EPP,
==> claim
<== E1284_SYS
Claim Status: -8
ieee1284 Claim: : No such device or address

Interestingly, lsmod now shows a bunch of modules related to parallel ports.

Code:

/sbin/lsmod
Module                  Size  Used by
lp                     14893  0
parport_pc             27777  1
ppdev                  12613  0
parport                37256  3 lp,parport_pc,ppdev

(more unrelated stuff omitted....)

Who can explain what I'm seeing, and how to gain exclusive access?

uname -a
Linux 2.6.9-42.0.3.ELhugemem #1 SMP Thu Oct 5 15:24:32 CDT 2006 i686 i686 i386 GNU/Linux

Thanks.

--- rod.